Electronic fuel tank system having cam actuated venting with canister line isolation

Abstract

An evaporative emissions control system configured to recapture and recycle emitted fuel vapor on a vehicle fuel tank is provided. The control system includes a first and second vent line disposed in the fuel tank, a first and second vent valve, a vent shut-off assembly, a purge canister and a control module. The vent shut-off assembly selectively opens and closes the first and second valves to provide overpressure and vacuum relief for the fuel tank. The control module regulates operation of the vent shut-off assembly based on operating conditions to vent the first and second vent valves to the purge canister. The vehicle fuel tank comprises a saddle tank having first and second lobes and a raised portion arranged generally at a top portion of the fuel tank. The first vent valve is arranged generally in the first lobe and the second vent valve is arranged in the raised portion.

What is claimed is: 
     
         1 . An evaporative emissions control system configured to recapture and recycle emitted fuel vapor on a vehicle fuel tank, the evaporative emissions control system comprising:
 a first valve that is configured to selectively open and close a first vent;   a canister vent line that vents from the fuel tank to a purge canister;   a canister vent valve that is configured to selectively open and close a canister port fluidly coupled to the canister vent line;   a vent shut-off assembly that selectively opens and closes the first valve and the canister valve to provide overpressure and vacuum relief for the fuel tank; and   a control module that regulates operation of the vent shut-off assembly based on operating conditions to vent the first valve and canister valve.   
     
     
         2 . The evaporative emissions control system of  claim 1  wherein the vent shut-off assembly is disposed internal to the vehicle fuel tank. 
     
     
         3 . The evaporative emissions control system of  claim 1 , further comprising:
 a second valve that is configured to selectively open and close a second vent; and   wherein the vent shut-off assembly comprises a cam assembly having a cam shaft that includes a first cam that selectively opens and closes the first valve, a second cam that selectively opens and closes the second valve and a canister cam that selectively opens and closes the canister valve.   
     
     
         4 . The evaporative emissions control system of  claim 3  wherein the second valve selectively opens and closes a second port that is configured solely as a refueling port, wherein during refueling, the second valve is opened by the second cam until the control module controls the vent shut-off assembly to close the second valve based on a fuel level reaching a predetermined level corresponding to a “Fill” position. 
     
     
         5 . The evaporative emissions control system of  claim 4 , further comprising an actuator assembly that drives the cam assembly, the actuator assembly including a motor. 
     
     
         6 . The evaporative emissions control system of  claim 3 , further comprising:
 a third valve fluidly that is configured to selectively open and close a third vent; and   wherein the cam shaft includes a third cam that selectively opens and closes the third valve.   
     
     
         7 . An evaporative emissions control system configured to recapture and recycle emitted fuel vapor on a vehicle fuel tank, the evaporative emissions control system comprising:
 a first vent valve disposed on the first vent line that is configured to selectively open and close a first port fluidly coupled to the first vent valve;   a second vent valve disposed on the second vent line that is configured to selectively open and close a second port fluidly coupled to the second vent valve;   a vent shut-off assembly that selectively opens and closes the first and second valves to provide overpressure and vacuum relief for the fuel tank;   a purge canister fluidly coupled to the vent shut-off assembly through a canister vent line;   a control module that regulates operation of the vent shut-off assembly based on operating conditions to vent the first and second vent valves to the purge canister; and   wherein the vehicle fuel tank comprises a saddle tank having a first lobe, a second lobe and a raised portion arranged generally at a top portion of the fuel tank, wherein the first vent valve is arranged generally in the first lobe and the second vent valve is arranged in the raised portion.   
     
     
         8 . The evaporative emissions control system of  claim 7  wherein the vent shut-off assembly is disposed internal to the vehicle fuel tank. 
     
     
         9 . The evaporative emissions control system of  claim 8 , further comprising:
 a first vent line connected between the first valve and the first vent;   a second vent line connected between the second valve and the second vent, wherein:   the first vent line has a first diameter that supports a first flow rate; and   the second vent line has a second diameter that supports a second flow rate, the second flow rate being higher than the first flow rate, the second vent tube configured to support vapor flow during a refueling event.   
     
     
         10 . The evaporative emissions control system of  claim 8  wherein the second diameter is at least twice as large as the first diameter. 
     
     
         11 . The evaporative emissions control system of  claim 8  wherein the second vent valve is positioned at an elevated location relative to the first vent valve when the vehicle is on level ground. 
     
     
         12 . The evaporative emissions control system of  claim 11  wherein during a refueling event, as fuel rises within the fuel tank, the first vent valve becomes submerged while the second vent valve remains in vapor space at the raised portion. 
     
     
         13 . The evaporative emissions control system of  claim 12  wherein the control module communicates with the vent shut-off assembly during the refueling event to close the first vent valve prior to closing the second vent valve. 
     
     
         14 . The evaporative emissions control system of  claim 9  wherein the vent shut-off assembly comprises a cam assembly having a cam shaft that includes a first cam and a second cam. 
     
     
         15 . The evaporative emissions control system of  claim 14  wherein the first and second cams have respective cam profiles that correspond to at least a fully opened valve position, a fully closed valve position and a partially open valve position. 
     
     
         16 . The evaporative emissions control system of  claim 15  wherein the first and second vent valves are caused to selectively open and close based on rotation of the respective first and second cams to deliver fuel vapor through the respective first and second vent lines. 
     
     
         17 . The evaporative emissions control system of  claim 16 , further comprising an actuator assembly that drives the cam assembly, the actuator assembly including a motor, wherein the motor comprises a direct current motor that rotates a worm gear that in turn drives a drive gear coupled to the cam shaft. 
     
     
         18 . The evaporative emissions control system of  claim 9  wherein the second port is configured solely as a refueling port, wherein during refueling, the second valve is opened by the second cam until the control module controls the vent shut-off assembly to close the second valve based on a fuel level reaching a predetermined level corresponding to a “Fill” position.